To what do the A and B measurements refer?

[chintonmd]

Greetings to all. It would be very helpful if someone would explain what the "A" and "B" measurements refer to. Thanks. Chuck

[AERODYNE]

[chintonmd]

Merci beaucoup.

Also, what bearings should be used that are thin enough to work with 5mm aluminum? The closest I can come to 5mm aluminum sheet is 0.190 inches (5mm=0.196") The next size larger sheet available is 0.250" or about 6.6mm.

Charlie

[AERODYNE]

J'ai acheté ça :
Rotules GE6-ES
https://www.123roulement.com/rotules-GE6-ES.php

[chintonmd]

Thank you. That is very helpful.